ATP-induced mucin release from cultured airway goblet cells involves, in part, activation of protein kinase C.

Abstract

Extracellular nucleotides stimulate mucin release by binding to the P2u receptor coupled to phospholipase C via G proteins (Br. J. Pharmacol. 103:1053-1056, 1991; Am. J. Respir. Cell Mol. Biol. 8:121-125, 1993). In the present study, we intended to investigate pathways downstream to the phospholipase C activation which is responsible for adenosine triphosphate (ATP)-induced mucin release in hamster tracheal epithelial cells in primary culture. We have found that: (1) Ca2+ ionophores (A23187 and ionomycin) did not affect mucin release even at 1 microM; (2) thapsigargin (10 microM), either alone or in combination with ATP (20 microM), did not enhance mucin release over its respective control group; (3) pretreatment of hamster tracheal surface epithelial (HTSE) cells with 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid-acetoxymethyl ester (BAPTA-AM) (50 microM) did not inhibit ATP-induced mucin release; (4) 4beta-phorbol 12alpha-myristate 13-acetate (PMA, 1 microM) stimulated mucin release and its effect was completely blocked by protein kinase C inhibitors such as sphingosine (10 microM) and calphostin C (0.1 microM), whereas ATP-induced mucin release was blocked, only in part, by these inhibitors; (5) desensitization of protein kinase C by pretreatment with PMA inhibited the PMA-induced mucin release completely, however, ATP-induced mucin release was inhibited only partially. We conclude that mucin release by ATP does not require an increase in the intracellular Ca2+ level but involves the activation of protein kinase C. The results also suggest the presence of another mechanism separate from the phospholipase C-protein kinase C pathway for the ATP-induced mucin release.

Protein Kinase Cδ Regulates Airway Mucin Secretion via Phosphorylation of MARCKS Protein

“…35,36 Involvement of PKC activation during airway mucin secretion in response to various secretagogues has been reported. 9,[37][38][39] However, involvement of any specific isoform(s) has not been fully characterized.…”

MARCKS Protein Is a Key Molecule Regulating Mucin Secretion by Human Airway Epithelial Cells in Vitro

“…1 (3)(4)(5)(6) or cGMP-dependent protein kinase (PKG) (7) in the secretory process. However, coordinated interactions or "cross-talk" between these two protein kinases in regulation of mucin secretion have not been demonstrated, nor have signaling events downstream of protein kinase activation that ultimately lead to the exocytotic release of mucin granules been elucidated.…”

P2Y2 agonist induces mucin secretion via Ca2+- and inositol 1,4,5-triphosphate-dependent pathway in human middle ear epithelial cells

“…UTP up-regulate mucin gene expression and stimulate mucin secretion via Ca 2+ -independent, diacylglycerol (DAG)-protein kinase C (PKC) and extracellular signal regulated kinase (ERK) mitogen-activated protein kinase (MAPK) pathway in hamster tracheal epithelial cells (Chen et al, 2001;Ko et al, 1997). However, depletion of intracellular Ca 2+ strongly suppressed the UTP-induced mucin secretion in our preliminary study.…”

“…Mucin release by ATP does not require an increase in the intracellular Ca 2+ level in primary hamster tracheal epithelial cells (Ko et al, 1997). On the other hand, nucleotide-induced mucin secretion is regulated independently with Ca 2+ and the PKC pathways in human nasal epithelial cells (Abdullah et al, 1997) and the spontaneously transformed rat goblet cell line, SPOC1 cells (Scott et al, 1998).…”

“…The activation of the P2Y 2 receptor by nucleotide has previously been shown to trigger the activation of PLC, and subsequently PKC. Both of these enzymes have been linked to mucin secretion in hamster (Ko et al, 1997), human (Kemp et al, 2004) tracheobronchial cell cultures or SPOC1 cells (Scott et al, 1998). However, the stimulatory effect of PKC varies according to the cell type (Knight et al, 1989).…”